A mixing chamber of a ventilation system is fed by at least two air-supplying ducts which can supply, for example, fresh air and/or recirculated air. A fan is connected downstream of the mixing chamber and generates a negative pressure in the mixing chamber. The mixed air is supplied via a duct removing air from the mixing chamber to the fan, where the air is mixed further and is finally conducted in the ventilation system to the space to be ventilated or the spaces to be ventilated, according to requirements. It is also known in this case to supply the mixing chamber with more than two ducts.
Each supplying duct has in each case a supply air flap which can have a plurality of flap leaves. In conjunction with this application, the supply air flap or the flap is the entire unit which has at least one flap leaf. In the case of large supplying ducts, a plurality of flap leaves can also be combined to form flap units. The flap leaves of a flap unit are intercoupled in respect of the drive thereof. Said intercoupled flap leaves form a unit which in each case take up the same opening positions. A plurality of flap units here form a supply air flap. To differentiate therefrom, flap leaves are structurally combined in a frame. These are not flap units within the meaning of the disclosure.
As a rule, a plurality of flap leaves are provided per supply air flap or a plurality of flap units are provided per supply air flap. The flap leaves here are intercoupled in such a manner that the flap leaves each take up an identical opening position. The position of adjacent flap leaves with respect to one another is normally opposed, i.e. the opening angles are identical, since said flap leaves are intercoupled via a shaft and/or via a gearing, but the orientation of the flaps and the flap direction differ.
The opening positions of the supply air flaps of the two ducts supplying air to the mixing chamber are dependent on each other. For example, there is an opening position in one air-supplying duct of 90% and, in the other air-supplying duct of 10%. An opening position in both air-supplying ducts of 100% is also possible.
In the case of different opening positions, it is the aim of the mixing chamber to mix the air supplied via the two ducts of the mixing chamber together. However, it has turned out that, despite the negative pressure generated in the mixing chamber by a fan connected downstream of the mixing chamber, what are referred to as stratifications occur even downstream of said fan, that is to say that there can be, for example, temperature differences in the air in the duct removing air from the mixing chamber of up to 10° C. and more. This also occurs in the direction of flow downstream of the fan, by means of which the air of the two ducts is also mixed once again. The same applies to the other physical characteristic values, such as moisture, pressure and density, but also to the air quality, such as, for example, the oxygen content, pollutant content and CO2 content.
It is known to solve this problem by means of fixed internals in the mixing chamber or in the duct leading away from the mixing chamber, as a rule what is referred to as the supply air duct, for example by means of perforated plates, deflecting plates, induction devices and the like. However, a problem of said fixed internals is that the resulting increased flow resistance is permanent irrespective of whether stratification can occur. Said internals permanently reduce the efficiency of the ventilation system. A stratification in the duct leading away will, however, occur only if the mixing chamber is supplied air with different physical characteristic values and/or air qualities, for example air having different temperatures.